In an internal combustion engine equipped with a turbocharger (hereinafter simply referred to as supercharger) for rotating a turbine by using an exhaust energy, it is effective to enhance a supercharging efficiency of the supercharger in order to enhance the charging efficiency. Then, in order to enhance the supercharging efficiency, it is effective to increase an exhaust gas temperature.
For example, JP 2008-101502 A discloses a technology of acquiring a blow-through amount of a blow flowing through from a cylinder to an exhaust passage during an overlap period of one cylinder, and injecting, in a cylinder in the expansion stroke in the same period, a fuel for post combustion corresponding to the blow-through amount in addition to a normal fuel injection.
With this technology, by providing control so that the mixture ratio of the blown-through air to the fuel for post combustion is the theoretical air/fuel ratio, the mixture is combusted in the exhaust passage. As a result, the exhaust air temperature increases, and the energy for driving the turbine increases, which results in an enhancement in the charging efficiency. Moreover, the air/fuel ratio is stoichiometric, and hence is not reflected to an exhaust performance.